Extern all y-reenforced construction



. J. H. LEVERING EXTERNALLY HEENORCED CONSTRUCTION June 16, 1931- 6Sheets-Sheet Original Filed June 7, 1919 i f Y WTness y wf,

J. H. LEVERING EXTERNALLY REENFORCED CONSTRUCTION ma v tlullll vwantozJ. HLevern /wmg .J. H. LEVERING EXTERNALLY REENFORCED CONSTRUCTION June16, 1931. Re. 18,104 Original Filed June 7, 1919 6 Sheets-Sheet 3 JH.Leveri Hg J. H. LEVERING EXTERNALLY nEENFoRcEn cousTnucTIon June 16,1931.

,M4 lt e nwe mm .n s 6 9. l 9 1 7. m J d e .l i F 1 a n .1 g. i L o J.H. LEVERING EXTERNALLY REENFORCED CONSTRUCTION June 16, 1931.

Original Filed Jne 7, 1919 Re. 18,104 v6 Sheetsheet 5 J. H. LEVERINGEXTERNALLY REENFORCED CONSTRUCTION June 16, 1931. Re.- 18,104

original Filed June '7, 1919 e sneetsQ-sneet 6 WiTness 3mm Mi/n J H.YLevering Reissued June 16, 1931 v"Ul'sn'rslo STATES JAMES HENRYLEVERING, 0F LOS ANGELES, CALIFORNIA EXTERNALLY-REEN FORCED CONSTRUCTIONOriginal No. 1,643,275, 'dated September 20, 1927, Serial No. 302,470,led June 7, 1919. Application for reissue led September 19,

This invention and discovery pertains to the engineering art andparticularlyrelates tothe art of constructing dams for impounding orydiverting Waters for the purpose of conserving such waters anddeveloping hydraulic power. It is also applicable to bridges and otherstructures.

An object of this invention is to provide a practical. dam by means ofWhich it is made possible to safely dam any water channel or chasm, asfor instance, the chasm of the Colorado River Within the Grand Canyon ofthe Colorado, and to extend such dam, with practical ease and perfectsafety, to any desirable height; say for example, 120() feet more orless.

A dam for this purpose requires great strength and durability to preventfractures which may be caused by vibrations or stresses; also to preventdestructionror damage from seismotic action or other movements.

Another object is to avoid all danger of vibrations from overflowwithout constructing a separate spill-Way.

Other objects are low of construction. ,f

Another object is to preventV deterioration from the action of theelements.

Another object is to eliminate the necessity of raising scaffolding,forms lor supports during construction.

This-dam comprises a metal mono-plate face on a supporting element, suchas a lling, backing or core. i That is to say, I apply toa lling,.backing or core of concrete, or some suitable substitute therefor, aplate which is inherently integral throughout` an entire active face ofthe dam. Said plate is practicable-in the present state of theengineering art if constructed of pieces manufaccost and high speedturcd at the mill and welded together in situ An object is to take careof these require-Y ments. n i

A feature of the invention resides in the peculiar construction of thefacing-plate 1929. Serial No. 393,784.

with transverse grooves and ribs which serve,

in a novel and improved manner, several useful purposes, amongst whichmay be mentioned superior strength of plate and of the backing conformedthereto; superior adhesion to the backing; adaptability to carry thesuperimposed weight, as well as its own weight on the side walls or sidefootings instead of upon the base, which is thus relieved Anotheradvantage arising from this' transversely ribbed or grooved constructionas applied to the down-stream face of the` dam, is the baiiling anddissipating of lany overflow that may occur; and this obviates thenecessity of a water cushion at the foot of the dam. v

Another feature is the construction of the mono-plate by means ofoblique-arch ribs, which are welded to curved bonding plates to formtherewith a single continuous unitary armor plate extending in complexarch form from Wall to Wall ofthe channel andv from bottom to top of thedam.

Anotherfeature of theinvention is the construction of the dam` upon theprinciple of an abutment and arch combined, so that the structurefromwall to Wall of the chasm or channel and from baseto crest of thedam is at every point held in position by top, bottom and lateralabutments so that no local movement can occur.

Another feature resides in the novel combination of face plates andlilling, backing or core which results fromA the peculiar curves andshapes of the face plate or plates and the backing or core conformedthereto. This is especiallyT marked in the concrete construction wherethere is mounted on a face of the concrete core, and in combinationtherewith, an external armor plate Ahaving arched corrugations that areembedded in channel-like seats in the face of the core,

and affording a confining reenforcement for the core, whichreenforcement is bonded with the'core and is practically a unittherewith.

lIn this connection, however, it is noted thatby my novel constructionof the dam, a fractured orpulverized core would be held in position bythe integral plates on the Vup-streain side and the down-stream side,respectively, of the dam; so that it is practical to construct a damwith a gravel, a sand or an earth filling or core between-'saidup-streamand down-stream plates, it being understood that the thickness of thecore must be in correlation to the character of the material of whichthe core is made.

Another feature of this invention depends upon the principle governingthe contour of a vertical cross-section of the dam. I have 'discoveredthat by so constructing the darn that the general outline oftheup-stream and 'also the down-stream face of the damis, at

any vertical cross-section, from base to crest in the form of a spiralcurve in which the abscissa is equal to two-thirds power of the ordinate(LO=NX2/3) maximum resistance is developed. By constructing the dam"according to this formula the weight of the metal skin of the up-streamor down-stream face of the dam is so imposed upon the filling or core asto hold the material of the core whether of clay, gravel, broken stoneor concrete in place by gravity and yet to resist the up-lifting forceof any seepage Water that might, perchance, percolat-e in through thedam of given volume andl materialv constructed between spiral contours,inv its vertical and horizontal sections, will have a larger surface incontact with the floor and walls ofthe chasm than is possible withrformer constructions. This greater'contactV Aarea greatly increases theefficiency of the dam as a water seal, andthe large adhesion andfriction area thus provided, greatly increases the vstability of theVstructure by forming an impervious barrier to prevent seepage of waterthereunder to undermine i the dam.v

Y The principle of construction in the preferred form of this dam isthat the pripcipal and also the subordinate curves of the armor plate orplates are all concave externally and convex toward the filling, backingor core.V In' consequence of this novel construction, the effect of bothexpansion of theV metal armor by heat, and its contraction by cold, i'-to increase the frctional contact or v.across which the dam is built.

adhesive bond between the plate and the l, the arch rib and concaveplate construction set forth in the foregoing and the followingdescription.

The invention not only includes the .structure as a whole, but alsoincludes the specific parts constructed at the mill for this purpose;and includes the use of a specific construction of armor plate.V In thisconnection it is noted that in dams of considerable height or length thearmor may be steel plates having a thickness of'a'bout one inch, more orless, accordin to the requirements which will be well understood byengineers in view of this disclosure.

My improvementV in the engineering art involves the discovery that adamhaving an extreme coefficient of safety may be constructed bymanufacturing at almill, pieces of metal adapted to form a face'for thedam,

ed to the construction of the dam as herein set forth. V

' An object is`to provide a construction that `will investthe dam withan anchor system for securin the face plate'and the core or backingpositively together and to distribute the load throughout the structurein suchA a manner that there will not be any accumullated load upon anyfooting or other local portion ofthe structure.

Other objects, advantages and features of inventionlmay appear rfrom theaccompanying drawings, the subj'oined detail descrip#r tion and theappendedclaims.

The invention and discovery may be understood'by referencefto theaccompanying drawings.

Figure 1 is a view adapted to villustratev theproportions of the dam andthe general `lines of a vertical section of said dam taken mid-waybetween the side walls of the chasm Theelevational proportions shown inthis view are those adapted to the construction of a darn twelve hundredfeet high, and two hundred feet at the base. The lines on the up-streamand down-stream faces of the dam are intended to indicate thecorrugations or ribs thereon, but it must be understood that from thenature ofthe views it is impossible to show Vt-he s acing, proportions,form or confvrstruction o said ribs as they would be microscopic uponthe scale of the figures.` The plane of sight is slightly above thecrest of the dam so that the level crestof the dam appears in this viewto slope upward away from the middle section of the dam; it ispreferably level as seen in Fig. 9.

Fig. 1 is a perspective fragmental view of the dam at the crest andindicates in a eneral way the outlines of the faces of the am which itis impossible to show in Figs. 1, 2, 3.

Fig. 2 is a view analogous to Fig. 1 of a dam in proportions for fourhundred feet height.

Fig. 3 is a View analogous to Figs. 1 and 2 showing in general outline amid-cross section of an earth filled dam. In this view as in Fig. 2 noattempt is made to show the corrugations on the faces of the dam.

Fig. 4 is a plan of the dam indicated in Fior. 3.

Fig. 5 is a top plan of the dam indicated in Fig. 1.

Figs. 6, 7 and 8- are plan sections on lines indicated at w', m7, and wrespectively Fig. 1.

Fig. 9 is av fragmental face elevation of the dam corresponding to thatindicated in Figs. 1, 5, 6, 7 and 8. The parallel lines indicate theribbed or corrugated surface of the armor and are spaced apartinexaggerated proportions to avoid confusion of lines and the footings areindicated by dots at the ends of said lines.

Fig. 10 is afragmental vertical crosssection on a larger scale than thepreceding views, showing an upper part of an uncompleted mono-platedouble-armored concreteiilled dam in course of construction, a fragmentof only one armor-plate being shown.

Fig. 11 is a transverse section of one of 4 the rib-forming girder-beamsdetached and on a scale larger than that of Fig. 10.

, Fig. 12 is an isometric view of an end of one of the beam-likemill-length sections adapted to the construction of the girder- 45 beamsat the dam.

Fig. 13 is la diagrammatic end plot of the form of ygirder-beam milllength vshown in Figs. 11 and 12.

Fig. 14 is a vertical section on line x,

5 Fig. 15 of one of the footings in situv ready to have a mill-lengthgirder beam-like section welded thereonto for constructing one of theribs. v

Fig.l15 is a view of the front face of one I of the footings with stubin place.

plate 1 may be constructed of vpanels or strakes a and ribs orgirder-beams b made up respectively of plate-like mill lengths orsections c acting as bonding members vand beam-like mill lengths orsections d, (Figs. 10-13) integrally united in situ by any wellknownprocess of welding as by flame or by electricity. f

In Figs. 10, 16,- 17 and 18, splice bars e are shown for use in unitingthe ends of the mill length plate sections. Said splice bars may or maynot be constructed with anchor devices and in Fig.y 17 a splice bar ehaving an anchor is shown in cross-section with the ends of twoplate-like mill lengt-hs c in plan section, laid in thefchannels 3 ofsaid bar, ready for electrical or iame Welding to the splice bar. V Theanchors of the splice `bars are shown in Figs. 10, 16` and 17. 'Theplate-like mill lengths c maybe formed at the mill or place ofmanufacture to conformto its place in the completed structure.Preferablythe core or backing 2, is faced on the up-stream side and alsoupon thedoWn-stream side. by face-plates of the same character.

As shown in Figs. 1, 2 and 3 these faceplates are constructed to a,contour, vertically frorn the base to the crest atthe midplane andthroughout the vertical cross section of uniform height, respectivelyconforming, to spirals projected in accordance with the formula(LO=NX2/3) in which the abscissa from the base'to the crest at suchvertical cross sections is equal totwo-thirds power of the ordinate ofthe height, that is in which the length LO', of the ordinate ofdeparture' horizontally from the face of the dam is equal to thetwo-third power of the distance H from the base of the dam to theintersection of the line with ordinate LO of ycross sections of equalVlengths, from midplane to abutment, to spirals projected in ac:-cordance withthe formula above stated.

For illustration, in Fig. 1, assuming the height to be 1000 feet, LO isthe ordinate at the one thousand foot height, M is the terminal of theordinate and N is .the point of intersection. M-N is equal to 10002/3viz;- 100 ft. At the five hundred foot ordinate L0, Q is the terminaland R the point of intersection with the' curve. Q-R` is equal tothetwo-third power of 500; i. e., 5002/3. In Figs. 5', 6, 7 and 8,the-bases B, of the horizontal spirals lare at the points respectively,of the intersection of the spiral with the supporting wall; and the apexA, is at the center of the structure. Inl Fig. 5 the length of thecentral ordinate vof departure LO is equal to the two-third power of525; the chasm being 1050 feet wide at the top or crest 18 ofthe dam.

f It isthus seen that the dam in the preferred form consists of a corethicker at the Vbase 19 or abutment 20 than at the crest 18 -'and alsothicker at 'its'abutments lateral terminals 21 thanat the thinnestmiddle or key 22.

In Fig.-.10, the mill sections a of the plate are shown hatched in onedirection and the ribs-b hatched in another direction to indicate theindependence of such sections prior to their welding together at thejoints f. Y Said mill sectionsof .the plates are bent to'predeterminedcurves, both longitudinally and transversely to` mainly conform to-thepredetermined curves ofthe proposed structure, and are bent at top andbottom edges to t the beams to which they vare to be welded. The ribbedmill sections are constructed at the mill to conform tothe longitudinalmargins of the plate sections respectively, and said rib vSections maybe constructed at the mil-l to a. novel. crossA section as shown in Fig.11` forthe double purpose of securing thegreatest strength and stiffnessfor Va given amount ofy metal, and the greatest conveniencefor fitting`and Welding the plate sections thereto. f

' The ribor girder beam consists of a rolled steel member with anappropriate weight, which, for a. dam of this size,` will be, say,

210 pounds per running foot. The appropriate curvedvbonding plates a forthe armor vface plate of a dam of the size indicated in Figs. 1 .ando-9,may be made of nolled steel one inch in .thickness and 72 inches wide inthe fiat and curvedas at g., to engage the entire curved surfaceh, ofthe webv and base of the beam d as indicated at f, Fig. 10. Theconstruction and dimensions of the beams may vary with' the size andduty of structures respectively for which of the ribs b `and con- Y theyare made.

The arrangement cavities Vof the face 'plate Voni-the downstream side ofthe dam operates to avoid all necessity ofa separate spill-way and of awater cushion. The upper face of each rib forms a baille for the waterflowing-over the crest of the dam so that thefall of the watery isbroken at each rib line. Furthermore, the

ribs overhang one another to form air spaces t,

and channels .90, sov that in addition to strengthenin the down-streamface of the dam said ri operate toward suction and aeration of thewater. The concave surface of the plates, together with theoverhanging," ribs and action of the air superficial to vthe v platesand below the ribs respectively, tend to give the impinging water avortiginous motion causing the water to commingle with 'the air` andotherwise dissipate so that the force of its impact is minimizedreduced.v Y The face plates or greatly on both` the .up-stream side andthe down-Stream side areshown concaved; being inv the form of a doublearch..V v v The curved plates and ribs in combinaltion with the coreform a multiple arch face in which eachiplate with its .abutting ribs'each form an arched member that not only constitute,V an arch member.The strakes curve upwardagainst the gravity load but inwardly-toward themiddle of the core; thus, under all conditions, tending to preserve theintegrity of the masonry or filled core. f. l y

The effect of movements due to temperature stresses, Whether from a riseor drop in temperature, Will result, in either event, to

cause the metal to press yagainst the face of the core and nottorseparate from it. This tends to maintain 'the rigidity vand strengthofthe dam under allpossible conditions.

The splice bars e for use at the weldjoints between the ends of theplates c are preferably constructed of anchor form. as detailed inFigs.10, 16, 17' and 18. The web 4 and foot 5 of the anchor conform,substantially,

tothe web and base of the girder beam sec` tions; being substantially.of fish tail form c in cro-section.

The head or outer -rib of the anchor splice bar is constructed withouter and lateral ribs 6, 7, 8, formingfchannels 9, in which the edgesl() of the-plate-like,mill-sections c will be laid preparatory toWelding. The weldingl of the .plates to ribs andsplicebars for anystrake is effected in the usual manner-of electric or flame Weldingbefore thel concrete is poured at that height. The anchor y5 terminatesshort of the endsv of the splice bar to give clearance at 11 for thebodies'of the girder beams b.

The ribs or girders are supported in place 1 by footings 12 shown in`detail in Figs. 14 and .15, said footings comprising blocks of cast orforged `steel,\having conca-vities 13l at the back, and rib, orgirder-beam stubs 14 fixed in and projecting from the front.`

-These footings are vembeddedin cement 15 in the channeled or otherwiseprepared Walls 16,'of the chasm that is to be dammed, and the ribs orgirder beams are attached thereto in any suitable manner as bywelding,thus` -making the metal footing 12 and beam stub 14 integralwith one another. v

Inpractice, preparatory to final construction, the footings, the millsections of ribs and plates and the necessary broken-rock or.

other aggregates and hydraulic cement are assembled at thedam site, andthe bed and side walls of the chasm or channel across which thestructure is to be built is prepared toan appropriate contour for thereception of the foundation and side rfootings of the dam. The penstocksfor an outlet omitted fromYV the views vfor the convenience of thedraftsman and toavoid confusion of lines,

.may then be placed in position-immediately lIIO uprg the foundation orat any height desi Y The construction of the dam proper may then becarried on as follows The up-stream and down-stream armor will becarried upward at least one strake above the core which is poured andtamped in glace between the plates so as to conform to an be in contactwith the inner surface of the steel.

The steel work is carried upas follows: The footings are anchored to theinside of the can on along a predetermined contour, prefera ly toconform to the spiral memtioned above. The footings 12 respectivelycontaining the stubs of the girder beams, are anchored firmly in placealong the predetermined contour, and by welding the connecting rib millsections d and the footing stubs of the beams together, they are madeinto continuous longitudinal members, preferably rising toward themiddle, but of the same general elevation at the wall terminals. Thecurved plates or bonding members o are then placed in position on theupper side of the girder b and together with the splice bars, e arewelded into final position. Upon the top edge of the plate panel thusformed, another course of beam sections thus formed is laid and weldedto the footing stubs and together, and to the supporting, bonding platesand anchor splice ars; and in this Way the construction is carried upone strake in advance of the filling or core, as stated above. The steelmembers, previously having been formed to the specified curves, willmake the arch design as shown in the drawing sprin both upwardly ytowardlthe crest of tlndam and inwardly toward the middle of the filling orcore of the dam. In this way, when concrete aggregate is used, the steelmembers permanently make required forms for the concrete without theexpense of any temporary supports, scaffoldin or forms.

t is understood that some of the advantages of constructing the dam witha cross- Sectional contour, conforming to the formula stated are asfollows:

It develo the required strength and friction area. t at would be shownby an` arch of several times its weight built between parallel segments.

The weight of the steel armor is disposed so as to protect the base ortoe from rupture by upward pressure or percolating water.

In the instance shown in Fig. 1 it may be assumed that the dam is either1000 or 1200 feet in height, and that in the latter case it tion plottedwith a unit of measurement equal to 12/10 of al foot so that there are1000 units of measurement in the distance from base to crest of dam. Thepurpose of changing the length of the unit of measurement according tothe increased height is to avoid bringing the upper portion of a dam ofgreat height into too close conformity to a vertical. l

It is noted that by the applicationiof the novel principles ofconstruction herein set forth, the thinnest part of the drain is at themiddle of the dam crest, and that such l'middle is the unitary crown ofa double reverse arch. In any instance, however, before deflection couldoccur in the damshown, both the concrete core and the concaveV armorplate on the face receding from the pressure source would have to besheared. rIn addition to this the webs of the splice bars would have tobe sheared.

Another feature of strength resides in the multiple arch constructiondeveloped by the arrangement of curved panels as set forth.

A further advantage arises from the concave face dam construction inthat the hydrostatic pressure of the impounded water is radial toV theconcavity and consequently two-thirds, more or less, of the pressure isdirected towards the walls and floor of the chasm. By reason of thedouble concave construction shown in Fig. 4 only the upper middle thirdworks as an arch, and the extreme thirds at both ends and a measurableportion at the bottom work as abutments. That is, the thrust of thepressure exerted on the portions of the damadjacent each side and for aconsiderable distance across the chasm from each side, is on lines whichwill project into the side walls of the chasm, consequently only themiddle span of the dam is unsupported directly b said sidewalls. SeeFigs. 4 and 5. 'Iihe portions supported by the sides may be consideredabutments and the portion not so supported may be called the archproper.

By reference to Figs. 5 and 6, it will be seen that the arch properextendsl less than one-third the length of the dam, as indicated Y bythe chord C, the arch resting on the abutments D.

The dam is thus composed of -a combination of arch and abutments whichaffords greater strength for a` given volume or mass of material thanpossible with former const-ructions.

It is thus seen that the invention is a broad departure from formerpractice as to the various principles, parts and combinations'of partsset forth, as well as in the completed structure, and that the inventionmay be applied in various forms within the judgment of the constructor;and that various features 'may be changed or omitted without deparhashad the contour of its vertical cross-secture from the invention inother respects, and therefore, I do not limit the invention to thespecific details, although it includes the same.

By providing a composite stress-resisting struct-ure in which theportion for resisting f compression is reenforced externally byopelement, secure maximum strength, and

avoid all likelihood of breaking, shattering or weakening thereenforcedfportion of the structure by any force insufficient` .to rendi the reenforcing portion.y

I have also provided for maximized frictional and anti-seepage contactby introducing the inverted arch into dam construction, whereby sucheffect is maximized for a given mass.

It is also understood that though the central upper member of the dam isshown as a reverse arch, it may be differently constructed, and that Ihave only illustrated the invention in that form which I at present deemmost desirable for the purpose of constructin a dam.

claim. 1. A structural unit havinga face', cross sectional contours ofwhich substantially conform, respectively, from abutment to midplanealong the crest and also from base'to crest of such unit, to a formulain which the abscissa is equal to the two-,thirds power of the ordinatewith the parts of greatest curvature at the base and at the'abutments ofsaid unit.

2. A structural unit having a corrugated face, cross sectional contoursof which from base to crest and'from the abutments to middleplane alongthe crest between the abutments conform generally to a formula in whichthe abscissa is equal to the two-thirds power of the ordinate withthe'parts of greatest curvature at the base and at the abutments of saidunit.

' 3. A structural unit comprising a core and an inherently unitary metalface, contours of vwhich face substantially conform respectively,frombase to crest and from abutment to mid-plane along the crest to aformula in which the abscissa from base toward the crest or fromabutment toward middle plane along the crest isequal to the two-thirdspower of the ordinate with the parts of greatest curvature at the baseand at the abutments of said unit.

4. A structural unit comprising a core and an inherently unitarycorrugated face, contours of vwhich face substantially conformrespectively from base to crest and from abutment toward mid-plane alongthe crest, to a formula in which the abscissa is equal to the two-thirdspower of the ordinate with the so parts of greatest curvature at thebase and at the abutments of said unit.

5.` A dam having up-stream and downstream faces that conformsubstantially, in vertical cross section from base to crest, to a C5formula in which the abscissa is equal-to twothirds power of theordinate with the pointofmaximum curvature at the base of said unit. Y

6. A dam having a transversely corrugated conca-ve downstream face, thecorrugations being overhanging ribs forming air Vspacesr beneath theribs, respectively.

7. A dam comprising a core and a verticall ly and transversely concavemetal face sustaining and externally reinforcing said core.

8. A dam having its down-stream face curved away from the crest andformed with alternate ribs and concavities arranged transversely of thechannel in which the dam is u ribs and vertically conc'aved inter-ribplate-- like members externally reenforcing said core. l

10. A dam comprising a concrete core and having a laterally concavedup-s'tream and down-stream faces, terminating in enlargedlateralabutments, and metallic face-plates made up of ribs and verticallyconcaved inter-rib plate-like members surfacing and externallyreenforcing said core. l f

11. A dam comprising a plate composed of .arched ribs and plate-likemembers integrally united; said plate-like members being longitudinallycurved and arranged to form grooves on one side and corrugations on theother side of the plate; and a core externally reenforced by said plate.

12. A dam comprising a core terminating in enlarged lateral abutmentsand having external metallic reenforcements, the said reenforcementscomprising outwardly projecting ribs and vertically concaved inter-ribplate-like members. y

13. A dam comprising a core terminating in enlarged lateral abutmentsand having external metallic reenforcements, the -said reenforcementscomprising a plurality of outwardly projecting ribs of the same size andvertically concave inter-rib plate-like inembers, the faces of said dambeing curved from the top to the bottom thereof so that each of theprojecting ribs will intercept the Water falling over the said dam.

14. A dam having laterally concaved upstream and down-stream faces,comprising a concrete coreterminating in enlarged lateral abutments andmetallic face-platesA made up of outwardly projecting ribs-andvertically concaved inter-rib plate-like members.

15. A dam having a concave face and rib's projecting from such face andinclined upwardly toward the middle of such face.

16. `A dam having a concaveface and ribs projecting from such face andinclined and arched upwardly toward the middle of such ace.

17. A dam comprising a core having upstream and downstream facesoppositely curved longitudinally to form the dam with increasingthicknesses from the mid-plane toward the end abutments thereof, said-upstream and downstream faces being curved inwardly throughout frombase to crest, and

a metal face sustaining and externally reenforcin the upstream anddownstream faces 1 of sai core.

a JAMES HENRY LEVERING.

